In general, a light emitting diode (LED) is being widely used as a light source for a display device because of its small size, low power consumption and high reliability. The light emitting diode uses a compound semiconductor such as aluminum gallium arsenide (AlGaAs), gallium aluminum phosphide (GaAlP), gallium phosphide (GaP), indium gallium aluminum phosphide (InGaAlP), gallium nitride (GaN), and the like. The light emitting diode includes an n-type semiconductor layer formed of the compound semiconductor, an active layer on the n-type semiconductor layer, and a p-type semiconductor layer on the active layer. An n-electrode and a p-electrode are electrically connected to the n-type semiconductor layer and the p-type semiconductor layer, respectively. When an electric current is applied to the n-electrode and the p-electrode from the outside, current is injected to the active layer, thereby emitting light.
To increase luminous efficiency of the light emitting diode, the current applied to the light emitting diode needs to be spatially diffused for the uniform flow through the entire active layer. The n-type semiconductor layer is formed of a material having a relatively good conductivity, but resistance that blocks diffusion of the current still exists. For the uniform diffusion of the current, various arrangements of the electrodes have been made. The electrode arrangements according to the conventional art are disclosed in U.S. Pat. No. 5,652,432, No. 6,307,218, and No. 6,344,665, and U.S. Patent Laid-open publication No. 2004/0140473.
According to the conventional art, an n- or p-electrode is disposed at an edge of an emission surface of the LED. Such an electrode arrangement causes the distance between the electrodes to increase, and thus the resistance is increased to thus limit driving at a low voltage. Alternatively, the n-electrode and the p-electrode are connected to respective bonding pads in the form of a plurality of fingers or branches, and the fingers or branches of the n- and p-electrodes alternate each other. However, this alternating arrangement of the electrodes are problematic in that it covers a large area of the active layer, lowering the luminous efficiency.